1. Field of the Invention
This invention relates to the field of surfboards. More specifically, the invention comprises a surfboard with vents that transfer air from the deck to the bottom, where a portion of the air becomes entrained in the water flow and creates an air-film beneath the board.
2. Description of the Related Art
Surfboards were invented by ancient Polynesians. They were originally carved from straight sections of tree trunk and were typically 3-4 meters (10-15 feet) in length and weighed as much as 70 kg (150 pounds). The sport of surfing expanded greatly in the years following World War II. The expansion of the sport was propelled in part by the availability of new materials for constructing surfboards. The widespread availability of fiberglass was a significant factor.
Modern surfboards are typically made by bonding a high-strength “skin” material to a low density/low strength “core” material. The core material is often polyurethane or polystyrene foam, but may also be natural materials such as balsa wood. The skin is made by covering the core with a material such as woven fiberglass cloth. The woven cloth is bonded to itself and the core using polyester or epoxy resin.
FIG. 1 shows a plan and elevation view for a representative surfboard. Those skilled in the art will now that a virtually endless variety of surfboards are now in common use. Thus, the board shown in FIG. 1 is properly viewed as one example among many possibilities. However, all surfboards share some common characteristics and these have been labeled in FIG. 1 in order to benefit the reader's understanding.
The top of the surfboard is known as deck 12. The forward portion is known as nose 14, while the aft portion is known as tail 16. The board's lateral boundaries are generally referred to as “rails” (left rail 18 and right 20). The board's downward facing surface is known as bottom 24.
FIG. 1 is not labeled as “prior art” because the surfboard depicted includes the present invention (vents 26). Its other features are common to prior art boards, however, and thus it is still useful for discussing the background of the invention. It is common for modern surfboards to include one or more skegs 22. These prevent lateral slipping and aid in turning the board. Other features may be included, such as an attachment point for a “leash” that is used to link the board to one of the surfer's ankles.
The board shown in FIG. 1 is known for being fairly agile, meaning that it can be quickly turned. It has a fairly broad beam and a relatively short length (in comparison to traditional “long boards”). When a rider is riding the board such as shown in FIG. 1, only the aft portion will engage the water. How much of the board is in contact with the water depends on many factors. However, it is common for at least a substantial portion of the board's forward region to be free of the water.
The surface friction generated by the interaction of the board's bottom with the water is a significant factor in determining the speed the surfer is able to achieve. Surfboards are commonly smoothed and waxed in order to minimize the friction between the board's bottom and the water. However, smoothing and waxing will only increase the board's speed to a certain extent. It is desirable to further increase the board's speed by further reducing friction. The present invention provides such an enhancement.